Talking with local reporters after a town hall in Tennessee last Thursday, Corker, who had so far declined to criticize the president's controversial remarks about a violent white supremacist rally in Charlottesville, Virginia, argued that anything short of "radical changes" in the White House would leave the nation in "great peril."

"The president has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate in order to be successful," Corker said. "He also recently has not demonstrated that he understands the character of this nation. He has not demonstrated that he understands what has made this nation great and what it is today ... and without the things that I just mentioned happening, our nation is going to go through great peril."

Sanders refused to respond to the comments when a reporter raised them at the briefing, instead saying the remarks did not warrant a reaction.

"I think that's a ridiculous and outrageous claim and doesn't even require a response from this podium," Sanders said.